Well, maybe is not exactly a part II, but is an extension of the previous article I wrote about this ND filter, the Light Craft Workshop Fader ND Mk II, very long name for a not that good filter IMHO.
Anyway, in the previous post I was saying that that filter is a big disappointment if coupled with my old, and now sold, Sigma 10-20mm f/4-5.6 HSM EX DC, while with another zoom lens I tried, a longer Sigma 17-50 I didn't have any big problems.
So today I decided to go out and do some extra tests with my brand new wide angle lens, the Canon 17-40mm f/4 L USM.
Now, bear in mind that all the three wide lenses I tried have the same filter size, 77mm, so we cannot really point at the filter size as one of the possible causes. But how it did perform with the Canon L(uxury) lens? Same as the Sigma 17-50 (which shares a very similar focal range) or like the Sigma 10-20?

Well, to be fair I was expecting to have a similar result to the first one, has the two lenses have the same filter size and very similar focal lenght, but unfortunately I was wrong. I did perform bad, not as bad as the 10-20, but very close.
But let me show you some pictures, and I want to start with the shortest focal length, 17mm, which I tested in all the lenses and I set the filter not at the maximum power, but just the mark before the max, so I wanted to be a bit nice with this filter a give it a bit of handicap, and once again, this photos are the RAW converted in JPG, no post production, not even minimal, just opened in LR4 and exported, that's it.

17mm - f/14 - 30 sec - ISO 160

Unlike the Sigma 10-20 in this case I didn't have a X shape, but two big areas on the top right and bottom left corner, where it underexpose the areas by approx 1.5 stops, and makes this photo totally unusable.

24mm - f/14 - 30 sec - ISO 160

Same story here at 24mm, it just crop the scene but still the two areas are pretty evident. Probably here is even worst than the 20mm of the Sigma 10-20.

35mm - f/14 - 30 sec - ISO 160

At 35mm essentially we crop out the dark areas, even if we can still see that that corners are still a bit underexposed than the rest of the picture. I know that these pictures are a bit underexposed in general, but I didn't want to burn the sky to make more clear the "effect" of this filter.

40mm - f/14 - 30 sec - ISO 160

Last picture, 40mm, now the effect is definetely gone or correctable in post production, which it makes the filter very usable here, but again, what's the point to have a filter used mostly by landscapes photographers, who generally shoot at very wide focal lenghts, to work only with a nearly to normal focal length? I'm not saying that you cannot take landscapes with long lenses, I did it many times with my 135mm or even the 70-200mm, but we are talking about the 1% of the cases, and if I go out to photograph landscapes, I tend to go out with the widest lens I have and that's it, and I presume that most of other landscape photographers would do the same.
So again, this ND Filter is fine in most of the cases or al least for normal to tele lenses, and it's definitely good for videographers, but it's a total waste of money if you are a landscape photographer.